<template>
	<div >
		<h1>当前求和为:{{sum}}</h1>
		<!-- 强制网number转换 -->
		<select v-model.number="n">
			<!-- 加了: 之后变成js表达式，解析后就是纯粹的数字 -->
			<option value="1">1</option>
			<option value="2">2</option>
			<option value="3">3</option>
		</select>
		<button type="button" @click='increment'>+</button>
		<button type="button" @click='decrement'>-</button>
		<button type="button" @click='incrementOdd'>当前求和为奇数再加</button>
		<button type="button" @click='incrementWait'>等一等再加</button>
	</div>
</template>

<script>
	export default{
		name:'Count',
		data(){
			return{
				// 用户选择数字
				n:1,
				// 当前的和
				sum:0
			}
		},
		methods:{
			increment(){
				this.sum += this.n
			},
			decrement(){
				this.sum -= this.n
			},
			incrementOdd(){
				if(this.sum%2){
					this.sum += this.n
				}
			},
			incrementWait(){
				setTimeout(()=>{
					this.sum += this.n
				},500)
			},
		}
	}
</script>

<style scoped>
	button{
		margin-left: 10px;
	}
</style>
